Hmmm... chips... chips.... Dinan is popular.... another popular one is the Jim Conforti Shark Injector... I use that... I know people that have used the Dinan.. and gotten most of the same experiances from it.... either way... it helps once you mod the engine more and more.... Jim makes a good CAI too... you should look into that one... you can find all of this at the TMS web site... .its..
www.turnermotorsport.com Good Luck... its often a very crazy adventure into mods of a BMW... have fun though.. thats the whole point.